1. Field of the Invention
This invention relates to froth flotation processes for the recovery of metal values from base metal sulfide ores. More particularly, it relates to processes that employ sulfide mineral collectors comprising certain N-butoxycarbonyl-O-alkylthionocarbamate compounds which exhibit excellent metallurgical performance over a broad range of pH values.
2. Description of the Related Art
Froth flotation is a widely used process for beneficiating ores containing valuable minerals. A typical froth flotation process involves intermixing an aqueous slurry containing finely ground ore particles with a frothing or foaming agent to produce a froth. Ore particles that contain the desired mineral are preferentially attracted to the froth because of an affinity between the froth and the exposed mineral on the surfaces of the ore particles. The resulting beneficiated minerals are then collected by separating them from the froth. Chemical reagents known as xe2x80x9ccollectorsxe2x80x9d are commonly added to the slurry to increase the selectivity and efficiency of the separation process, see U.S. Pat. No. 4,584,097, which is hereby incorporated herein by reference.
Froth flotation is especially useful for separating finely ground valuable minerals from their associated gangue or for separating valuable minerals from one another. Because of the large scale on which mining operations are typically conducted and the large difference in value between the desired mineral and the associated gangue, even relatively small increases in separation efficiency provide substantial gains in productivity.
Unexpectedly, it has now been found that N-butoxycarbonyl-O-alkylthionocarbamates selected from the group consisting of N-butoxycarbonyl-O-methylthionocarbamate, N-butoxycarbonyl-O-ethylthionocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-O-butylthionocarbamate, N-butoxycarbonyl-O-pentylthionocarbamate, and N-butoxycarbonyl-O-hexylthionocarbamate are particularly effective in froth flotation processes. A preferred embodiment provides a froth flotation process for beneficiating an ore, comprising: forming a slurry comprising water and particles of an ore, the ore containing sulfide minerals; intermixing the slurry with effective amounts of a frothing agent and a collector to form a froth containing beneficiated sulfide minerals; and collecting the beneficiated sulfide minerals; the collector comprising an N-butoxycarbonyl-O-alkylthionocarbamate selected from the group consisting of N-butoxycarbonyl-O-methylthionocarbamate, N-butoxycarbonyl-O-ethylthionocarbamate, N-butoxycarbonyl-O-propylthiononocarbamate, N-butoxycarbonyl-O-butylthionocarbamate, N-butoxycarbonyl-O-pentylthionocarbamate, and N-butoxycarbonyl-O-hexylthionocarbamate.
These and other embodiments are described in greater detail below.